Purple tea water extract blocks RANKL-induced osteoclastogenesis through modulation of Akt/GSK3ß and Blimp1-Irf8 pathways.

A number of studies demonstrated that some tea extracts exert inhibitory effects on osteoclastogenesis induced by receptor activator of nuclear factor κB ligand (RANKL). However, the effect of purple tea, a famous tea in China, on osteoclastogenesis remains unclear. In this study, a water-based purple tea extract (PTE) was found to suppress osteoclast formation, osteoclastic resorption pit area formation, and F-actin ring formation within RANKL-stimulated bone marrow macrophages (BMMs). Furthermore, our results demonstrated that PTE could inhibit expression of master transcription factors NFATc1 and c-Fos and their target genes DC-STAMP, Ctsk, and Atp6v0d2. Western blot analysis revealed that PTE treatment led to reduced RANKL-induced phosphorylation of Akt and GSK3ß without altering transient activation of NF-κB and MAPKs (p38, JNK, ERK1/2) signaling. In addition, the results demonstrated that PTE treatment of RANKL-stimulated BMMs could down-regulate Blimp1 expression and up-regulate Irf8 expression. In summary, these results suggest that PTE treatment of RANKL-stimulated BMMs inhibited osteoclast differentiation via modulation of Blimp1-Irf8 and Akt/GSK3ß signaling pathways. Aligning with our in vitro results, in vivo PTE administration ameliorated bone loss in LPS-treated mice. Taken together, the results presented in this work suggest that PTE treatment possesses anti-osteolytic activity.

Ginseng oligosaccharides protect neurons from glutamate-induced oxidative damage through the Nrf2/HO-1 signaling pathway.

The effects of ginseng oligosaccharides (GSOs) on neuronal oxidative injury induced by glutamate (GLU) and the molecular mechanisms involved were investigated. Cell damage was assessed using MTT assays, and the lactate dehydrogenase (LDH) release rate and flow cytometry were used to detect the accumulation of reactive oxygen species (ROS) and mitochondrial membrane potential respectively. The levels of catalase (CAT) and glutathione (GSH) were measured in PC12 cells and Drosophila brain tissue. The climbing ability of Drosophila was observed. Levels of proteins, including Cyt C, Bcl-2/BAX, and Nrf2/HO-1-associated proteins, were determined by western blotting and immunofluorescence. It was found that GSOs reversed GLU-induced reductions in cell viability and the LDH release rate, and rescued ROS accumulation. GSOs also mitigated the deleterious effects of GLU on the mitochondrial membrane potential and Cyt C release, thus alleviating mitochondrial dysfunction, and increased GSH levels and CAT activity in both cells and Drosophila brain tissue. The climbing index in GSO-treated Drosophila was significantly higher than that in the tert-butyl-hydroperoxide-treated flies. Furthermore, GSOs protected cells against GLU-induced apoptosis by reducing the expression of the mitochondrial apoptosis-associated Bcl-2 family effector proteins and protected cells from GLU-induced oxidative damage by increasing the nuclear translocation of Nrf2 and HO-1 expression. These findings indicate that GSOs protect against GLU-induced neuronal oxidative damage through Nrf2/HO-1 activation.

Ginsenoside Rf inhibits human tau proteotoxicity and causes specific LncRNA, miRNA and mRNA expression changes in Caenorhabditis elegans model of tauopathy.

Under pathological conditions, human tau (htau) hyperphosphorylation promotes formation of proteotoxic intracellular amyloid aggregates that may underlie neurodegenerative diseases known as tauopathies, prompting researchers to develop treatments that inhibit htau aggregation as a promising therapeutic strategy. Ginsenosides, the main active constituents of Panax ginseng C. A. Meyer (ginseng), appear to inhibit tau aggregation and disassociation in tauopathy models, although their active components and molecular mechanisms are unknown. Here, we used a novel Caenorhabditis elegans (C. elegans) tauopathy model to identify ginsenoside monomers which may repress htau proteotoxicity. Our findings indicated that ginsenoside Rf prevented tau aggregation and reversed abnormal tau aggregation-induced phenotypes and alleviated neurodegeneration in worms. Notably, deep RNA-seq analysis of ginsenoside Rf-treated and untreated worms with tauopathy revealed that ginsenoside Rf altered expression levels of 24 up- and 36 down-regulated lncRNA transcripts, 32 up- and 22 down-regulated miRNAs and 65 up- and 30 down-regulated mRNA transcripts. Based on GO and KEGG pathway annotation analyses, identified mRNAs, miRNAs and lncRNAs-associated gene targets were functionally related to neuron-related terms (e.g., neuron development, axon and motor neuron axon guidance) and longevity regulating pathways. Importantly, RT-qRCR results suggested that 6 miRNAs (miR-786, miR-2208b, miR-34, miR-241, miR-247 and miR-4805), 8 lncRNAs (MSTRG.20812.2, MSTRG.22617.2, MSTRG.28210.13, MSTRG.5728.12, MSTRG.29708.1, MSTRG.3342.25, MSTRG.3342.31 and MSTRG.8841.8) and 7 mRNAs (nas-33, math-28, T14B4.19, col-17, rol-6, sqt-1 and irg-4) were potential targets of ginsenoside Rf inhibition of tauopathy. These results partially explain mechanisms underlying ginsenoside Rf-associated alleviation of htau proteotoxicity and will guide future strategies to discover potential therapeutic targets for preventing and alleviating tauopathies.

Salicylic acid in ginseng root alleviates skin hyperpigmentation disorders by inhibiting melanogenesis and melanosome transport.

Abnormal melanogenesis and melanosome transport can cause skin pigmentation disorders that are often treated using ginseng-based formulation. We previously found that phenolic acid compounds in ginseng root could inhibit melanin production and as a skin-whitening agents. However, mechanisms of action underlying effects of ginseng phenolic acid monomers on melanogenesis remain unclear. This study was conducted to investigate effects of salicylic acid, a main ginseng root phenolic acid component, on melanogenesis and melanosome functions in melanocytes of zebrafish and other species. Salicylic acid exhibited no cytotoxicity and reduced melanin levels and tyrosinase activity in B16F10 murine melanoma cells and normal human epidermal melanocytes regardless of prior cell stimulation with α-melanocyte stimulating hormone. Additionally, salicylic acid treatment reduced expression of melanogenic enzymes tyrosinase, tyrosinase-related protein 1 and tyrosinase-related protein 2, while reducing expression of their master transcriptional regulator, microphthalmia-associated transcription factor. Moreover, reduced phosphorylation of cAMP response-element binding protein was observed due to reduced cAMP levels resulting from salicylic acid inhibition of upstream signal regulators (adenylyl cyclase and protein kinase A). Furthermore, salicylic acid treatment suppressed expression of transport complex-associated proteins melanophilin and myosin Va in two UVB-treated melanocytic cell lines, suppressed phagocytosis of fluorescent microspheres by UVB-stimulated human keratinocytes (HaCaT), inhibited protease-activated receptor 2 activation by reducing both Ca2+ release and activation of phosphoinositide 3 kinase/AKT and mitogen-activated protein kinases and induced anti-melanogenic effects in zebrafish. Collectively, these results indicate that salicylic acid within ginseng root can inhibit melanocyte melanogenesis and melanin transport, while also suppressing keratinocyte phagocytic function.